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Download fileTiO2 Nanoparticle Uptake by the Water Flea Daphnia magna via Different Routes is Calcium-Dependent
journal contribution
posted on 2016-06-30, 00:00 authored by Ling-Yan Tan, Bin Huang, Shen Xu, Zhong-Bo Wei, Liu-Yan Yang, Ai-Jun MiaoCalcium
plays versatile roles in aquatic ecosystems. In this study,
we investigated its effects on the uptake of polyacrylate-coated TiO2 nanoparticles (PAA-TiO2-NPs) by the water flea
(cladoceran) Daphnia
magna. Particle distribution in these daphnids was
also visualized using synchrotron radiation-based micro X-ray fluorescence
spectroscopy, transmission electron microscopy, and scanning electron
microscopy. At low ambient Ca concentrations in the experimental medium
([Ca]dis), PAA-TiO2-NPs were well dispersed
and distributed throughout the daphnid; the particle concentration
was highest in the abdominal zone and the gut, as a result of endocytosis
and passive drinking of the nanoparticles, respectively. Further,
Ca induced PAA-TiO2-NP uptake as a result of the increased
Ca influx. At a high [Ca]dis, the PAA-TiO2-NPs
formed micrometer-sized aggregates that were ingested by D. magna and concentrated only in its gut, independent
of the Ca influx. Our results demonstrated the multiple effects of
Ca on nanoparticle bioaccumulation. Specifically, well-dispersed nanoparticles
were taken up by D. magna through endocytosis
and passive drinking whereas the uptake of micrometer-sized aggregates
relied on active ingestion.